1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, apparatus, and products for dynamic impedance matching for improved transient performance in a direct current-to-direct current (‘DC/DC’) converter for delivering a load to an electrical component.
2. Description of Related Art
Modern direct current-to-direct current (‘DC/DC’) converters utilize coupled inductors to reduce the effective inductance of the system when the DC/DC converter is delivering a constant load, thereby reducing power loss in the system. When the load to be delivered changes, however, low levels of inductance in the system can cause higher current ripples to filter by an output capacitor bank in the DC/DC convertor.
FIG. 1, for example, sets forth a prior art DC/DC converter that includes an indirectly coupled inductor. The example DC/DC converter (100) of FIG. 1 includes two power-switching phases (132, 134). Each phase includes two switches: a high-side switch (102, 106), and a low-side switch (104, 108). Each high-side switch (102, 106) includes a control input (110, 114) to activate the switch. Upon activation, each high-side switch (102, 106) couples a voltage source (VIN) to an indirectly coupled inductor (118). Each low-side switch (104, 108) also includes a control input (112, 116) to activate the switch. Upon activation, each low-side switch (104, 108) couples one coil of indirectly coupled inductor (118) to a ground voltage.
Coupled inductors come in two forms: indirectly coupled and directly coupled. The dots depicted in the example of FIG. 1 indicate the coupled inductor (118) is an indirectly coupled inductor. The dot convention specifies the flow of current in a coupled inductor as: when current flows ‘into’ one dot, current is induced in the alternate coil of the coupled inductor and flows ‘out of’ the other dot. Thus, in an indirectly coupled inductor, current generally flows in the same direction in both coils of the coupled inductor. The example prior art DC/DC converter (100) of FIG. 1 also includes an output capacitor (120) that operates as a lowpass filter and a load, represented by a resistor (122).
The example prior art DC/DC converter (100) of FIG. 1 can deliver power to one or more electrical components. The load to be delivered to an electrical component that is coupled to the DC/DC converter (100) may change. For example, the load to be delivered to an electrical component that is coupled to the DC/DC converter (100) may change when the electrical component powers up or powers down. Consider an example in which the DC/DC converter (100) is part of a mobile communications device. In such an example, the DC/DC converter (100) may be coupled to a battery that powers the mobile communications device. When a user of the mobile communications device ceases using the device, the user may click a button, switch, or otherwise cause the mobile communications device to enter into a power conservation state where various components of the mobile communications device (e.g., a touch screen display) are in a powered down state. In such an example, the load to be delivered to by the DC/DC converter (100) may decrease when the user forces the device into a hibernation mode. Likewise, when a user of the mobile communications device brings the device out of a powered down state by, for example, clicking a button that causes the touch screen display to turn on, the load to be delivered by the DC/DC converter (100) may increase. A change in the load to be delivered by a DC/DC converter (100) is referred to herein as a ‘transient event.’
The occurrence of a transient event may trigger unintended consequences. Consider an example in which the load to be delivered by the DC/DC converter (100) decreases significantly. Once the load transitions from a higher load to a smaller load, energy stored in the inductor (118) is dumped into an output capacitor (120) that serves as a filter in the DC/DC converter (100). If the capacitor (120) is inadequate, the output charge stored in the inductor (118) could ramp up the output voltage of the DC/DC converter (100), thereby causing the DC/DC converter (100) to deliver a voltage to a computing component that is outside of desired specifications.